What a bummer.
I put a lot of time and effort into fixing up my '47 2N last winter. I was going to sell it so that I could justify further tractor purchases (more like rescue projects). I had a serious buyer and we actually agreed on a price. But while showing it to him, the engine developed a misfire on #4. I lost the sale.
It might have been a good think in the end as I have used the tractor quite a bit since, even with just 3 cylinders popping. Still need to work on it.